Sheet supported articles coated with heat-activable tanning agents and improved methods of hardening said articles and related compositions

ABSTRACT

WHEREIN THE SUBSTITUENTS R AND R&#39;&#39; ARE SELECTED FROM HYDROGEN AND HALOGEN ATOMS AND ALKYL, CARBOXYL, ALKOXY, FORMYL, TERTIARY AMINO AND SULFO RADICALS. SOME SPECIFIC NEW COMPOUND OF THIS CLASS ARE DESCRIBED.   R,R&#39;&#39;,(CL-C(-CHO)=C(-COOH)-O-)-BENZENE   TANNING (HARDENING) AGENTS IN A COLLOID LAYER OF GELATIN OR THE LIKE ARE INACTIVE AT ORDINARY TEMPERATURES BUT ARE ACTIVATED AT TEMPERATURES ABOVE 70*C. TO RAPIDLY TAN THE COLLOID IN WHICH THEY ARE INCORPORATED. SUGGESTED USES ARE IN THERMOGRAPHY AND PHOTOGRAPHY. SPECIFIC EXAMPLES DESCRIBE VARIOUS GELATIN LAYERS CONTAINING THE HEAT-ACTIVATED HARDENERS. THE CLASS OF USEFUL TANNING AGENTS IS DESCRIBED BY THE FORMULA

United States Patent Olfice 3,579,374 Patented May 18, 1971 Int. Cl. C09d 37.04,- C08h 17/62 US. Cl. 117-164 16 Claims ABSTRACT OF THE DISCLOSURE Tanningthardening) agents in a colloid layer of gelatin or the like are inactive at ordinary temperatures but are activated at temperatures above 70 C. to rapidly tan the colloid in which they are incorporated. Suggested uses are in thermography and photography. Specific examples describe various gelatin layers containing the heat-activated hardeners. The class of useful tanning agents is described by the formula wherein the substituents R and R are selected from hydrogen and halogen atoms and alkyl, carboxyl, alkoxy, formyl, tertiary amino and sulfo radicals. Some specific new compounds of this class are described.

BACKGROUND OF THE INVENTION The invention relates to new chemical compounds and to use of a class of compounds comprising such new compounds as tanning agents for hydrophilic colloids such as gelatin and the like and particularly as tanning: agents for hardening hydrophilic colloid layers. As used in various embodiments, the invention relates to thermography and photography, particularly to hardening of gelatin and the like layers in thermographic and photographic recording elements by means of the new class of tanning agents.

Tanning agents of the class used in the present invention are distinguishable over usual tanning agents known in the art, such as formaldehyde, acrolein, glyoxal, dihydroxy ketone, fructose, mucochloric acid, and the like, in that the instant compounds do not tan gelatin compositions having a pH lower than or equal to at ordinary room temperatures as the customary tanning agents do, but they become very rapid tanning agents at activation temperatures above 70 C. By virtue of this selective hot-tanning property, these tamiing agents will find uses in which the ordinary room temperature colloid hardeners would not be used. The new tanning agents also may be used to replace conventional hardeners in some uses. The compound 2-phenoxy-3-chloromalealdehydic acid in which, according to the general formula described below, R and R are both hydrogen atoms, was described by Sawyer in Proc. Am. Acad. Arts and Sciences, 1893, 29, 242. We have not found reference to other compounds of the class described.

SUMMARY OF THE INVENTION An object of the invention is to provide new chemical compounds that are useful as gelatin tanning agents and to provide a class of compounds having unique properties as tanning agents for gelatin and related hydrophilic colloids. Another object is to provide improved processes for selective hardening of gelatin at elevated temperatures by means of the subject class of tanning agents. A particular object is to provide improvements in photography and thermography by means of this class of tanning agents and by means of the new tanning processes.

According to the present invention, we have discovered that compounds having the formula:

wherein each of R and R represents a member selected from the group consisting of hydrogen and halogen atoms, alkyl, carboxyl, alkoxy, formyl, tertiary amino and sulfo radicals attached to the ring, are useful as tanning agents for gelatin compositions and the like having the particularly useful property of being practically inert as tanning agents at ordinary room temperatures, e.g. below 50 C., but useful tanning at higher temperatures, i.e. at activation temperatures above C. when these compositions have a pH lower or equal to 5. Compounds of the class described, when incorporated in colloid layers having a pH lower or equal to 5, for example in layers containing gelatin, will be practically inert as tanning agents indefinitely at temperatures below 50 C. but can be activated as rapid tanning agents simply by elevating the temperature of the layer in which the compound is incorporated to an activating temperature above 70 C., usually in the range from l20-l50 C.

In use as a tanning agent, a compound of the class described is incorporated into a composition with a hydrophilic colloid such as gelatin or the like. For example, an aqueous coating composition containing gelatin and the tanning agent is coated and dried on a supporting surface. At ordinary room temperatures, the tanning agent in the mixed composition will remain inactive indefinitely. To tan the composition then, the temperature is elevated to an activation temperature above 70 C. at which the tanning agent acts rapidly to harden the gelatin.

Concentration of the tanning agent in the composition is relatively minor in proportion, usually in the range from about 1% to 6% by weight, based on dry weight of gelatin or other colloid to be tanned. At activation temperature the tanning agent acts fast, usually achieving the desired degree of hardening in a period from about a few seconds to about l0-l5 minutes, depending on various factors such as the degree of hardening desired, selection of the tanning agent, selection of the colloid, relative concentrations in the composition, activation temperature, etc.

The invention can be further understood by reference to the following description of specific examples in which we have set forth in detail our most preferred mode of carrying out the invention, as now contemplated.

DESCRIPTION OF SPECIFIC EMBODIMENTS (A) Preparation of compounds:

EXAMPLE I Preparation of 2-(p-carboxyp-henoxy)-3-chloromalealdehydic acid /C=O CHO COOH A solution of g. (3 moles) of sodium hydroxide in 1 liter water is cooled to 10 C. then over a period of 15 minutes 138 g. (1 mole) of p-hydroxybenzoic acid is added. After dissolution, the mixture is cooled again to 10 C., then 170 g. (1 mole) of mucochloric acid is added slowly keeping the temperature of the reaction mixture at 10 C., with constant stirring. Then the mix- 4 paper coated on both sides with polyethylene. Supports prepared as in Example HI are generally equivalent to the polyethylene coated supports with regard to smoothness and operability. As compared with preparation of polyethylene coated supports, the present supports are ture is allowed to return to room temperature as the 5 easier to manufacture and could be produced by much stirring is continued for approximately one hour, The simpler manufacturing machinery. Matrices prepared acsolution is poured into a mixture consisting of 1 liter concording to the patents mentioned above comprise an centrated hydrochloric acid, 1.5 liter cold water, and 500 emulsion layer coated on the support which is to be difg. ice. It is allowed to stand for one hour, producing ferentially hardened during processing. A particular ada whlte precipitate which is separated by filtrat1on and vantage for this use of a support prepared as described washed twice with 1 liter of cold water at 5 C. The in Example III is its stability and feedom from contamiproduct is then vacuum dried at 50 C., then sifted. A nation of the emulsion layer by migration of hardeners typical yield is 230 g., (86% yield) of white powder from the support gelatin layer to the emulsion layer. having a melting point of 180 C. Chlorine content cal- Supports similar to that prepared in Example III may culated: 13%. Found: 13.1%. also be used as a gel-subbed support for various photo- EXAMPLE H graphic emulsions. For example, a subbing of gelatin Following the procedures described in Example I mua l g gfi g tifgg gg ing zi ggii gfig cochloric acid is reacted with various substituted phenols h tanned rapidly by heating f example by contacting of the following formula with a heated iron as described in Example III, or harden- R ing of the sub might be achieved during drying simply HO by employing drying temperatures above 100 C. to eifect R simultaneously both drying and hot-tanning.

5 A thermo-tanned layer, as that described in Examwherein the substituents R and R are as described in the pie III coated on a support and tanned by heat, can be following table: used for preparing photographic products for receiving TABLE Chlorine, Chlorine, Yield, percent percent Product R R M.P. 0 percent theoretical found 2-(p;tert-penty1phenoxy)-3- p-Tert-pcntyl H 90-95 70 11.9 11.6

c loromaleaidehydic acid. 2-(p-octylphenoxy)-& pn-0cty1 H..... 65-70 70 chloromalealdehydic acid. 2-(pl-methoxyphenoxyy3- p-Methoxy H..... 95 60 14.0 14. 2

c loromalealdehydic acid. 2-(m-pentadecyD-3- m-Pcutadecyl H..... 40-45 48 chloromalealdehydic acid.

In preparing the p-methoxy derivative, the product may 40 silver images by diifusion transfer, the untanned negabe precipitated and dried by the same procedure described tive emulsion layer being able to be applied onto the in Example I; for the p-tert-pentyl and p-n-octyl derivatanned layer and then removed after development and tives it is more convenient to purify by means of prediffusion transfer by means of washing with tepid water. ciptation in a mixture of equal parts ethanol and water. A support with a tanned gelatin layer such as the one (B) Illustrating uses as tanning agent: describedin Example III can be used in photomechanical EXAMPLE HI reproduction, for example, in photolithographic processes 9 1 ti f 1 {n is added 3 parts tsetd fqr0gs9eg3pr1ntang1spl1zizgthose dfiscfilbed in French To an aqueous 5 o sou on o gea1 a n i w i t i are y Weight P 100 Parts gelatin of the hotjtaflnillg agent used that have a photographic emulsion layer coated on 2-p-carboxyphenOXy-3 alealdehydic acid. The 50 a polyethylene treated support. The polyethylene coated tanllngtagenills g d a fg g sfi gl zl gnfl gg 2 sgpptort can behreplaceg 1n prcI EcessesIbyHaiI siipplgrt an Wa er. $0 a 6 I a 0 a s cc Site as e one escrl e in xamp e n xaqueous lf solutifmi P i adlllsted to 7 P 4 ample III we have illustrated the invention by coating norm l SOdlum Y 'Q solullon- The final Solution 15 a gelatin layer on paper and then tanning gelatln layer. coated y conventlonal coating Pl'medllre 011 a Sheet It w ll be understood that gelatin layers containing the p wlllte bleached P p P p at a rate of tanning agent can also be coated on other suitable sup- (lledt gselgtin tP6I"[hdm g? olaf thg p g elf fl fig 2122; pots Isluclla l21s film sulrlaports cilf cellulose acetzfite,1 polyesters, aou ue 0 eacily an te ieaswe asot ersu ortso ass,meta, dried and then tanned with heat by applying a pressing wood, andthe1ike pp g iron to the layer of dried gelatin for 1-2 seconds. The EXAMPLE IV iron is heated to a temperature of 150 C. After heati I ing, the melting point of the treated gelatin coating is de- T1118 example illustrates use of gelatin layers tanned termined by dipping the coated and treated sample into 1n accordance w th the invention in a thermographic procan agitating tank filled with water and gradually raising ess. A solution 1s prepared consisting of 500 g. of 15% the temperature of the water at a rate of 3 C. per aqueous solution of bone gelatln, 1 liter water, 17 m1. of minute. Melting point of the layer which has been coated1 1/5% sapolnin dsolutlcflndandhe fl? 1s ad llllsted 53 g and subse uentl heat treat is over 100 C. A cOntro 4 norma so rum y I'OXI e. ere is t en a e coating co r itainir ig no tanning agent, after the same heat g. of 2 (p methoxyphenoxy) 3 chloromalealdehydic treatment melts at about 30 C. Before heat treatment acid in solution in a mixture of 100 ml. of water and the coatin with tanning agent melts at about 30 C. 100 ml. ethanol. Two grams of Prussian Blue are added and after tl iree months storage at room temperature, only to the solution. The finished solution is coated on paper slight variations in the melting pong: are detgcted. l I a; a covegage1 of 50 rnjg/drgfifif cliry gelatilrli. T516 piH o;

A paper sheet coated and tanne asin xamp e t e coate ge atin is a out e ayer ist en rie an is useful to replace supports for matrices used in processes exposed in a thermographic copying machine imagewise such as those described in French Pats. 980,481 and to heat the gelatin imagewise. The layer is washed with 1,092,692 in which the supports described consisted of tepid water at 33-40 C. which washes away gelatin in the unheated areas and forms a tanned gelatin image of blue color in the exposed areas,

In the foregoing description we have mentioned that activation temperatures for the hot-tanning agents is above 70 C. and the agents are inactive at room temperature. It should be explained that the rate of tanning may vary at various temperatures above 70 C. For example, at a lower activation temperature above 70 C., say at 100 C., the rate of hardening may be much slower than at a higher temperature say at 150 or 175 C. For most of the tanning agents of the class described, the most advantageous temperature for tanning will be in the range from 120-150 C. and useful activation temperatures may vary from about 100 C. up to about 200 C. Useful concentrations of the tanning agent in the colloid layer for most embodiments will be in the range from about 1 to about 6 parts tanning agent per 100 parts of dry colloid in the coating composition and for most uses the optimum concentration will be around 3 parts per hundred. Our tanning agents may be used as hardeners in photographic silver halide emulsion layers and in gelatin layers coated over silver halide emulsion layers. In such cases, use of these particular hardeners is advantageous because hardening can be delayed until after photographic processing. During processing the solutions will easily penetrate the colloid layers to facilitate rapid processing and the layer can then be hardened after processing to produce a finished photograph with a hardened colloid layer. Thus, the hardener can be incorporated in the emulsion during manufacture and its hardening effect can be delayed until after processing. The tanning agents or hardeners can be used to harden baryta layers used as undercoats in photographic printing papers instead of conventional hardeners. The present hardeners have the distinct advantage that they do not migrate to adjacent layers. Thus, they will not contaminate an adjacent layer such as a silver halide layer which might be coated over a layer containing the tanning agent, such as a baryta layer or a gelatin sub.

The invention has been described above with reference mainly to gelatin as a typical hydrophilic colloid that can be hardened by the tanning agents of the invention. More broadly, however, our invention includes uses of the class of tanning agents described when they are used as hardeners with other colloid compositions, for example with casein, albumin and similar natural hydrophilic colloids; with synthetic polymers useful as hydrophilic colloids, such as copolymers of acrylamide with other vinyl monomers such as methacrylic acid, allylacetoacetate, allylacetoacetamide and the like, imidized polyacrylamide, synthesized ampholytic polypeptides, polyoxyalkylene compounds, sulphobenzoate derivatives of cellulose and cellulose esters, polyvinyl alcohol derivatives and the like. The hardeners are effective in mixtures of hydrophilic colloids, for example in a mixture of gelatin with a synthetic polymer of the kind described above, or a mixture of other colloids.

It will be understood that modifications and variations may be made within the scope of the invention as described above.

We claim:

1. In a method of hardening a supported natural or synthetic organic hydrophilic colloid layer with a hardener which method comprises combining said colloid and said hardener and coating them on a support, the improvement which comprises employing as a hardener in a concentration from about 1% to about 6% by weight, based on a dry weight of said hydrophilic colloid a compound having a formula:

wherein each R and R is selected from hydrogen and halogen atoms and alkyl, carboxyl, alkoxy, formyl, tertiary amino, and sulfo radicals, and heat activating said coated combined colloid and hardener above about 70 C. for a time in the range from about a few seconds to about 15 minutes, sufficient to permit hardeneing of said colloid by said compound.

2. A method defined by claim 1 wherein said compouind is 2 (p carboxyphenoxy)-3-chloromalealdehydic ac1 3. A method defined by claim 1 wherein said compoulnd is 2-(p methoxyphenoxy) 3-chloromalealdehydic acl 4. A method defined by claim 1 wherein said compo uind is 2-(p-terbpentylphenoxy)-3-chloromalealdehydic aci 5. A method defined by claim 1 wherein said compound is 2-(p-octylphenoxy)-3-chloromalealdehydic acid.

6. A method defined by claim 1 wherein said compo llnd is 2-(m-pentadecylphenoxy)-3-chloromalealdehydic ac1 7. The method according ot claim 1 in which said colloid layer after coating has a pH of not more than about 5.

8. An article comprising a sheet coated with an organic hydrophilic colloid layer capable of being hardened by heating to an activation temperature above 70 C., said layer comprising a hydrophilic colloid and from about 1% to about 6% by weight based on the weight of the hydrophilic colloid of a compound having the formula wherein R and R are each selected from hydrogen and halogen atoms and alkyl, carboxyl, alkoxy, formyl, tertiary amino, and sulfo radicals.

9. The article defined by claim 8 wherein said hydrophilic colloid is gelatin.

10. The article defined by claim 9 wherein said selected compound is 2-(p-carboxyphenoxy)-3-chloromalealdehydlc acid.

11. The article defined by claim 9 wherein said selected compound is 2-(p-methoxyphenoxy)3-chloromalealdehydlc acid.

'12. The article defined by claim 9 wherein said selected compound is 2-(p-tert-pentylphenoxy)-3-chloromalealdehydic acid.

13. The article defined by claim 9 wherein said selected corgpound 1s 2-(p-octylphenoxy)-3-chloromalealdehydic aci 14. The article defined by claim 9 wherein said selected compound is 2-(m-pentadecylphenoxy-3-chloromalealdehydic acid.

'15. A composition consisting essentially of an organic hydrophlhc colloid and, in hardeneing concentration, a compound having the formula wherein each of R and R is selected from the group consisting of hydrogen and halogen atoms, alkyl, carboxyl, alkoxy, formyl, tertiary amino and sulfo radicals.

16. The composition of claim 15 having a pH of not more than about 5 and comprising gelatin.

(References on following page) References Cited UNITED STATES PATENTS Kress 117l56X Allen 96111 Burness et a1. 96-111 Ritson 117l56X Minsk et al. 96111X Jetfreys et a1. 117l56X Minsk et al. 96111X 5 WILLIAM D. MARTIN, Primary Examiner M. R. LUSIGNAN, Assistant Examiner U.S.C1.X.R.

Minsk et a1 106 -125X 6; 25065; 260-11? 

